Ubuntu 18.04: Download package source code with apt source

This article will describe enabling deb-src and download package source code with apt source.

1 Cannot run apt source by default

The apt source will be failed by default. This is because deb-src is comment out in /etc/apt/sources.list.

$ apt source linux
Reading package lists... Done
E: You must put some 'source' URIs in your sources.list

Enable deb-src.

$ grep '^deb ' /etc/apt/sources.list | \
  sed 's/^deb /deb-src /g' | \
  sudo tee /etc/apt/sources.list.d/deb-src.list
$ sudo apt update  -y

Install dpkg-dev package for dpkg-source command.

$ sudo apt install -y dpkg-dev

The apt source will work.

$ apt source linux
Reading package lists...
NOTICE: 'linux' packaging is maintained in the 'Git' version control
system at:
<snip>